The prevalence of personal computers and workstations in business and home environments drives the need for greater automation in self configuration at both the hardware and software levels. At the hardware level, to which the present invention pertains, it is important that the system be able to detect not only the presence or absence of interchangeable hardware modules but also attributes representing hardware characteristics such as speed or size. The hardware detection capability is particularly important when the addition or deletion of such hardware can be performed by relatively unsophisticated end users, such as through the simple insertion, deletion or exchange of printed circuit board type modules using sockets or connectors mounted in the data processing system.
The ability to detect both the presence and functionality of printed circuit boards or modules within a personal computer or workstation is applicable to user initiated additions or deletions of memory. Level 2 (L2) cache is a particularized form of such memory, often added by the end user in the pursuit of faster program execution rates. Industry standard L2 modules include present detect bits, but do not specify presence detect information allowing personal computers or workstations to differentiate between module types. This inability to differentiate between module types precludes the use of presence detect to differentiation between industry standard cache formats of 8 tag bit or 11 tag bit modules. The tag bits indicate the page count in main memory that the L2 module is capable of handling.
Thus, there has arisen the need for personal computers or workstations have the capability of discerning whether an L2 module that is detected as being present is either the 8 tag bit or 11 tag bit variety. Moreover, this capability must apply to modules which are designed and fabricated to an industry standard not directly indicating the tag bit capability.